ABSTRACT: The title compound, potassium diniobium vanadium phospho-rus deca-sulfide, KNb(1.75)V(0.25)PS(10), was obtained by reaction of the elements with a eutectic mixture of KCl/LiCl. It is isostructural with the quaternary KNb(2)PS(10), but the Nb sites are occupied by statistically disordered Nb (87.5%) and V (12.5%) atoms. The structure is composed of anionic (?) (1)[M(2)PS(10)](-) chains (M = Nb/V) separated from each other by K(+) ions. The chain is composed of [MS(8)] distorted bicapped trigonal prisms and [PS(4)] tetra-hedra. There are no inter-chain bonding inter-actions. The crystal used for the X-ray analysis was a racemic twin.
Project description:In comparison with a previous crystallographic study [Goh et al. (2002 ?). J. Solid State Chem.168, 119-125] of the title compound, silver diniobium tris-(disulfide) tetra-thio-phosphate(V), that reports a full occupation of the silver position and isotropic displacement parameters for the atoms, the current redetermination reveals a silver deficiency with a site-occupation factor of 0.88?(1) and reports all atoms with anisotropic displacement parameters. The structure of Ag(0.88)Nb(2)PS(10) is composed of (?) (1)[Nb(2)PS(10)] chains, which are built up from pairs of distorted bicapped trigonal-prismatic [NbS(8)] polyhedra forming [Nb(2)S(12)] dimers and of tetra-hedral [PS(4)] groups. These chains are connected via the statistically disordered Ag(+) ions, forming double layers. Adjacent layers are stacked solely through van der Waals forces into a three-dimensional structure. Short and long Nb-Nb distances [2.880?(1) and 3.770?(2)?Å, respectively] alternate along the chain and S(2) (2-) and S(2-) anionic species are observed.
Project description:The mixed-metal thio-phosphate, Nb1.18V0.82PS10 (niobium vanadium phospho-rus deca-sulfide), has been prepared though solid state reactions using an alkali-metal halide flux. The title compound is isostructural with two-dimensional Nb2PS10. [M 2S12] (M = Nb or V) dimers built up from two bicapped trigonal prisms and tetra-hedral [PS4] units share sulfur atoms to construct (1) ?[M 2PS10] chains along the a axis. These chains are linked through the di-sulfide bonds between [PS4] units in adjacent chains to form layers parallel to the ab plane. These layers then stack on top of each other to complete the three-dimensional structure with van der Waals gaps. The M sites are occupied by 59% of Nb and 41% of V and the average M-S and M-M distances in the title compound are in between those of V2PS10 and Nb2PS10. The classical charge balance of the title compound can be represented by [(Nb/V)(4+)]2[P(5+)][S(2-)]3[S(-)]7.
Project description:The quinter-nary thio-phosphate Cs(0.5)Ag(0.5)Nb(2)PS(10), cesium silver tris-(disulfido)[tetra-thio-phosphato(V)]diniobate(IV), has been prepared from the elements using a CsCl flux. The crystal structure is made up of (?) (1)[Nb(2)PS(10)] chains expanding along . These chains are built up from bicapped trigonal-prismatic [Nb(2)S(12)] units and tetra-hedral [PS(4)] groups and are linked through a linear S-Ag-S bridge, forming a two-dimensional layer. These layers then stack on top of each other, completing the three-dimensional structure with an undulating van der Waals gap. The disordered Cs(+) ions reside on sites with half-occupation in the voids of this arrangement. Short [2.8843?(5)?Å] and long [3.7316?(4)?Å] Nb-Nb distances alternate along the chains, and anionic S(2) (2-) and S(2-) species are observed. The charge balance of the com-pound can be represented by the formula [Cs(+)](0.5)[Ag(+)](0.5)[Nb(4+)](2)[PS(4) (3-)][S(2) (2-)](3).
Project description:The new layered ternary sulfide, Nb(1.30)Cr(0.70)S(5), niobium chromium penta-sulfide, is isostructural with the solid solution Nb(1+x)V(1-x)S(5) and belongs to the FeNb(3)Se(10) structure type. Each layer is composed of two unique chains of face-sharing [NbS(8)] bicapped trigonal prisms (m symmetry) and edge-sharing [MS(6)] (M= Nb, Cr) octa-hedra (m symmetry). One of the two metal sites is occupied by statistically disordered Nb and Cr atoms, with 0.3 and 0.7 occupancy, respectively. The chains are connected along the c axis, forming two-dimensional layers, which then stack on top of each other to complete the three dimensional structure. As a result, an undulating van der Waals gap is found between the layers.
Project description:The title compound catena-poly[potassium [tri-?-disulfido-?-tetra-thiophos-pha-to-di[niobate(IV)/tantalate(IV)(0.885/0.115)]]], has been obtained through the reaction of the elements with KCl. The title compound is isostructural with KNb2PS10, with the Nb sites occupied by statistically disordered Nb (88.5%) and Ta (11.5%) atoms. The structure is composed of anionic ? (1)[M 2PS10](-) chains along  (M = Nb/Ta) and K(+) ions. This chain is built up from distorted bicapped trigonal prisms [MS8] and [PS4] tetra-hedra. There are no inter-chain bonding inter-actions, except for electrostatic and van der Waals forces. The S2 (2-) and S(2-) anionic species and the M (4+)-M (4+) pair [M-M = 2.8939?(3)?Å] are observed. The classical charge balance is represented by [K(+)][M (4+)]2[PS4 (3-)][S2 (2-)]3.
Project description:The new mixed-metallic phase, niobium vanadium nona-selenide, (Nb(2-x)V(x))Se(9) (0.18? x ? 0.59) is isostructural with monoclinic V(2)Se(9). The structure is composed of chains of bicapped trigonal-prismatic [MSe(8)] units. The metal (M) site is occupied by statistically disordered Nb [0.706?(5)] and V [0.294?(5)] atoms. Two trigonal prisms are linked by sharing a recta-ngular face composed of two Se(2) (2-) pairs. Through three edging and capping Se atoms, the chains are extended along . The chain shows alternating short [2.8847?(7)?Å] and long [3.7159?(7)?Å] M-M distances. The structure shows a wide range of Se-Se inter-actions. In addition to the Se(2) (2-) pairs of the recta-ngular face, an inter-mediate Se?Se separation [2.6584?(5)?Å] is found. The amount of each metal can vary, [(Nb(2-x)V(x))Se(9), 0.18 ? x ?m 0.59] and they seem to form a random substitutional solid solution. The M-M distances increase gradually by increasing the amount of Nb atoms. The classical charge-balance of the compound can be described as [M(4+)](2)[Se(2) (2-)](2)[Se(5) (4-)].
Project description:The quaternary thio-phosphate, Cs(0.49)NbPS(6), caesium hexa-thio-niobiophosphate(V), has been synthesized by the reactive halide flux method. The title compound is isotypic with Rb(0.46)TaPS(6) and is made up of a bicapped trigonal-biprismatic [Nb(2)S(12)] unit and a tetra-hedral [PS(4)] group. The [Nb(2)S(12)] units linked by the [PS(4)] tetra-hedra form infinite chains, yielding a three-dimensional network with rather large van der Waals gaps along the c axis in which the disordered Cs(+) ions reside. The electrons released by the Cs atoms are transferred to the pairwise niobium metal site and there are substantial inter-metallic Nb-Nb bonding inter-actions. This leads to a significant decrease of the inter-metallic distance in the title compound compared to that in TaPS(6). The classical charge balance of the title compound may be represented as [Cs(+)](0.49)[Nb(4.51+)][P(5+)][S(2-)](4)[S(2) (2-)].
Project description:A single crystal of penta-lanthanum dizinc stannide, La(5)Zn(2)Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo(5)SiB(2) structure type, which is a ternary ordered variant of the Cr(5)B(3) structure type. The space is filled by bicapped tetra-gonal anti-prisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetra-gonal anti-prisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m); La2 (4/m..); Zn (m.2m); Sn (422).
Project description:The title hafnium germanium telluride, HfGeTe(4), has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe(4) is isostructural with stoichiometric ZrGeTe(4) and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe(4) adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetra-hedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps.
Project description:Crystals of La(2)Pb(SiS(4))(2), dilanthanum(III) lead(II) bis[tetrasulfidosilicate(IV)], were obtained from the La-Pb-Si-S system and structurally characterized using X-ray single-crystal diffraction. The La and Pb atoms are coordinated in bicapped trigonal prisms of S atoms, with the Si atoms in tetrahedra. An occupational disorder of the La and Pb centres was refined for one position in the structure. The bicapped trigonal prisms and tetrahedra share edges. A gap located 2.629 (1) A from the sulfide anions was found around the coordination polyhedra, which makes La(2)Pb(SiS(4))(2) a prospective material in crystal engineering. The Si and one S atom lie on a threefold axis.